What is the required compaction for cohesive materials below 0.6 m (2 ft) of road base material?

The required compaction for cohesive materials below 0.6 m (2 ft) of road base material is specified at 95% of the maximum density. This requirement is crucial for ensuring that the subgrade and base layer have the necessary strength and stability to support the above structures, such as the pavement surface. Cohesive materials, often comprising clay or silt, exhibit different compaction characteristics compared to non-cohesive materials, necessitating a higher compaction percentage to achieve the desired performance.

Achieving 95% compaction assists in minimizing settlement, reducing the potential for future pavement deformation, and improving overall load-bearing capacity. This level of compaction is typically determined through standardized testing methods like the Proctor test, which helps establish the optimum moisture content and maximum dry density for the material in question. Maintaining this standard ensures the longevity and durability of the road infrastructure, making it a standard practice in road construction.